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Reference Number: AA-01534// Views: AA-01534// Created: 2018-10-02 19:45:57// Last Updated: 2020-02-11 15:01:38
Q&A
Oregano card shows a time offset of 37 seconds ahead of expected UTC time

Description

When feeding the Oregano card with a valid IRIG-B synchronization signal from GPS, the Oregano card shows an offset of 37 seconds.


Solution

There are two systems of time: UTC (Coordinated Universal Time) and TAI (International Atomic Time). In 2020, the TAI time is ahead of the UTC time by 37 seconds. This difference is increasing through the years (source).


When the 'Synchronization mode' is set to Precise Time Protocol (PTP), the Oregano card outputs TAI time by default. Therefore, if the synchronization mode is set to 'PTP', there will be an offset of 37 seconds compared to the UTC.


However, the C37.118 protocol is using the UTC time. Therefore, for C37.118, there are three options:


1- Offset manually by 37 seconds in the model

2- Change the synchronization mode to IRIG-B. However, you will need to provide the synchronization signal on the x4 connector.

3- This offset  can be corrected in RT-LAB's advanced options as shown in the image, the command "-U 0" must be set in the "Advanced options" field. *





* Note: as of RT-LAB 2019.1, there was an update on the Oregano firmware and the Advanced option does not work anymore.